Cyclic Shear-Lag Model of Steel Bolt for Concrete Subjected to Impact Loading

Abstract

This paper presents a new cyclic piecewise linear pull-out push-in shear-lag material model representing the local bond behavior of preconstruction-installed steel anchor bolts for concrete. Impact loading resulting from a Schmidt hammer is used to evaluate the bond quality between the steel bolt and the surrounding concrete. The impact loading results in microcracking at the interface of steel bolt. The bond between the steel bolt and the surrounding concrete is modeled as a nonlinear interface. Each loading cycle is modeled by dividing it into six portions, namely elastic loading, interfacial cracking, unloading, reloading in the push-in direction accompanied by interfacial cracking, unloading, and reloading in the pull-out direction. The model incorporates stiffness degeneration caused by interfacial cracking and stiffness recovery caused by the lateral pressure effect along with Poisson’s effect. Rules formulated by trial and error for plotting cyclic pull-out push-in deformational response of steel bolts are presented. The validity of the presented rules is judged by comparing their cyclic deformational response with a finite-element simulation, and experimental deformational response and good agreement is found. The developed cyclic rules can be used for simulating the deformational response of preconstruction-installed steel anchor bolts.